Dortmund president Dr Reinhold Rauball has admitted that he fears that Kagawa will not sign a contract extension while United have indicated that they are ready to offer the 23-year-old a three-year deal worth £95,000-a-week, according to Bild.

Goal.com understands that Sir Alex Ferguson has a long-standing interest in the Japan international, who is valued at around £12 million as his existing contract expires next summer.

United are in the hunt for a creative midfielder and have added Kagawa - who has been in stunning form this season and scored 16 goals - to the likes of Luka Modric and Eden Hazard on their list of potential targets.

The Premier League leaders are also attracted to the commercial benefits of signing Kagawa in light of the club’s huge fanbase in the Far East and the financial success of Ji-Sung Park’s time at the club.

Kagawa, who has also been linked with Arsenal and Chelsea, is believed to have been offered £2.4m-a-year to extend his contract until 2016, doubling his existing salary. However, he could earn four times his current wages at Old Trafford.

"For me it's still a toss-up, although I have a slight tendency towards skepticism," Rauball told Bild.

Dortmund hope to extend Kagawa's stay, but have a ready replacement with Marco Reus joining the club from Borussia Monchengladbach in July.

Kagawa moved to Dortmund from Cerezo Osaka in 2010 and scored against Gladbach last week as Jurgen Klopp’s side secured a second successive Bundesliga title.